更改存储过程显示“Argument data type ntext is invalid for argument 1 of left function”错误

Question

我有这个存储过程：

ALTER PROCEDURE [dbo].[OptimizedGetArticlePostAMP] 
     (@PostID int)     
--[ OptimizedGetArticlePostAMP] 678161      
-- 732490        
AS
BEGIN
    DECLARE @SectionId int, @datediff int                                    
    DECLARE @postdate datetime

    SELECT 
        P.PostId, P.SectionID, P.PostName, 
        MP.MetaTitle, P.Postdate, P.PostAuthor, P.IsApproved,
        MP.Metadescription, MP.Metakeywords, 
        P.TotalViews, P.Subject, P.FormattedBody,                      
        MV.Isvideo, MV.VideoCode, MV.VideoCaption, 
        A.DrComment, A.SpanishURL, PS.RedirectUrl,
        MP.Canonical as Canonical, PS.StatusId,
        dbo.[ GetCommentCountForPost](@PostId) as TotalReplies,  
        PRD.StoryImage, PRD.StoryContent,                             
        MH.LastModifiedDate,
        REPLACE(LEFT(P.FormattedBody, CHARINDEX('</strong>', P.FormattedBody) - 1),'<p><strong>By','') <--This Line shows **error**
    FROM 
        csposts P 
    LEFT JOIN
        NewsletterDetails A ON (P.Postid = A.postid)       
    LEFT JOIN
        PostStatus PS ON (PS.postid = p.postid)
    LEFT JOIN  
        PostMetatags MP ON (P.postid = MP.Postid)              
    LEFT JOIN
        postVideo MV ON (P.postid = MV.Postid)
    LEFT JOIN 
        CSPostAttachments PA ON P.PostId = PA.PostId 
                             AND PA.contenttype LIKE 'audio/mpeg' 
                             AND PA.FILENAME LIKE '%.mp3' 
                             AND PA.isremote = 1
    LEFT JOIN  
        PostRelatedData PRD ON P.PostId = PRD.PostId
    LEFT JOIN  
        PostReferences PR on P.PostId = PR.PostId
    CROSS APPLY 
        (SELECT TOP 1 LastModifiedDate 
         FROM ArticleModifiedHistory 
         WHERE ArticleModifiedHistory.Postid = P.postid 
         ORDER BY LastModifiedDate desc) MH
    WHERE
        P.Postid = @Postid     
END

由于我使用了 LEFT 函数，它显示以下错误：

参数数据类型 ntext 对左函数的参数 1 无效。

请让我知道我需要进行哪些更改才能使其运行。

Answer 1

你可以替换

LEFT([Column], 123)

通过

SUBSTRING([Column], 1, 123)

SUBSTRING 很乐意接受 ntext 数据类型。

参考：SUBSTRING，LEFT

Answer 2

Left 函数不接受 ntext 数据类型。就像 gofr1 所说的首先将其转换为 nvarchar 或使用接受 ntext 参数的子字符串函数。